Ernest jules pierre



(No Model.)

. E. J. P. MERGADIER.

TELEPHONE. No. 447,194. I Patented Feb. 24, 1891.

NiTED STATES PATENT Frrcn.

ERNEST JULES PIERREMERCADIER, OF PARIS, FRANCE.

TELEPHONE I.

SPECIFICATION forming part of Letters Patent No. 447,194, dated February 24:, 1891.

Application filed May 26, 1890. Serial No. 353,162. (No model.) Patented in France May 30,1888, No. 190,909: in England July 1'7, 1888,1T0. 10,363; in Germany August 16, 1888.1T0.49,213, and in Belgium August 28, 1888,110. 83,056-

To ctZZ whom it may concern.-

Be it known that I, ERNEST'JULES PIERRE MERCADIER, a citizen of the Republic of France,-and a resident of Paris, France, have invented certain new and useful Improve-' ments in Telephones, (for which I have obtained Letters Patentin France May 30,1888, No. 190,909; in England July 17, 1 888, No. 10,363; in Germany August 16, 1888, No. 49,213, and in Belgium August 28, 1888, No. 83,056,) of which the following is a specification.

Ordinary magneto-telephone receivers are constructed with a diaphragm having its edge or edges clamped, and such diaphragm has the peculiarity that it will respond to all rates of vibration. in fact it must be capable of thus responding in order to adapt it to the reception of articulate speech or other compleX sounds.

My present invention has for its object the construction of a telephone which will respond to one rate of vibration only, or to one rate of electrical undulations generated by and in accordance with one definite rate of vibration and to no others, so that the instrument may be used in asystem of multiple and harmonic telegraphy involving the use of a number of differently-tuned tuning-forks as transmitters, and which,'theret'ore, require an equal number of receivinginstruments, each responding to the action of one tuning-fork and to no others, and I have given to telephones of this character the name Monotelephone, and have shown and described the same, without claiming it, however, in my Letters Patent No. 420,884, dated February 4, 1890, in connection with my system of multiple telegraphy.

In the accompanying drawing, which forms a part of this specification, I have illustrated in cross-section one form of my monotelephonic receiver embodying my invention; but I desire it to be understood that I am not limited to the details of construction herein, shown, since the same may be variously changedwithout departing from my invention.

Referring now to the drawing, there is shown an electro-magnet 18, having a coil of rather high resistance mounted in a suitable casing 19, with its free active pole 20 slightly projecting through a partition 21. Upon this partition are mounted three guides 22, arranged radially on the partition, if the same is circular, and by preference the guides are equally spacechso that the sectors into which the circleis thus divided are equal. Upon each guide is mounted a stud 23, adjustable upon the guide, and if these studs are each adjusted at the same distance from the center of the partition they mark the. corners of an equilateral triangle inscribed in a circle whose radius is equal to that distance. I

A diaphragm 24,01? magnetic material, preferably iron, is loosely placed upon the supporting-studs 23, so that the center of the diaphragm coincides with the center of thepart ition 21. Now it is a well-known fact that if a circular resonant disk is set into vibra- 79 tion by a tone which is the first harmonic of its fundamental tone a concentric nodal line will be formed on the disk, the radius of which nodal line is a trifle less than twothirds of the radius of the disk.

' In my monotelephone I adjust the supporting-studs 23 so that when the diaphragm is placed upon them they correspond to the nodal line of the first harmonic of the diaphragm, and a diaphragm thus supported will perceptibly respond to a rythm due to that first harmonic and to no other. I am thus enabled to make a telephone responding to one particular sound only, and telephones of this or similar construction must be used in my system of multiple telegraphy set forth in my aforesaid Letters Patent.

The nodal line of the first harmonic of the diaphragm cannot be determined with absolute accuracy, and therefore, as a rule, the first adjustment of the studs 23 will not be perfect, and in order to compensate for this defect I use an adjustingweight 25, which may be a short heavy cylinder of brass resting upon the diaphragm and connected on one side with a rubber or other elastic cord 26, and on the other with a thin wire or cord 27, both of which are fixed at their other ends to winding-pegs 28, and by turning the latter one way or the other the adj usting-weight 25 may be brought to any desired position upon the diaphragm, and by a proper adjustment of the same the defect or adjustment of the supporting-studs 23 may be neutralized and the diaphragm tuned to respond powerfully to the first harmonic of its fundamental note. In fact the pitch of the diaphragm may be varied within a major second by proper adjustment of the weight 25, although such violent adjustments are not necessary in practice. Sound-conveying tubes 29 29, terminating in ear-pieces 30, are arranged to convey the sound from both sides of the diaphragm to the listener, who will preferably use both ear-pieces.

If in place of a circular diaphragm one of rectangular form is used, the supporting-studs 23 will be so adjusted that two of them will be on one of the two nodal lines of the fundamental sound of the diaphragm, which are at about twenty-two on e-hundredths ofthe whole length, measured from either end, and the other supporting-stud will be on the other of said nodal lines. A telephone thus constructed will respond to the rythm of its fundamental tone only.

It will thus be seen that in my monotelephone the resonant plate acted upon by the electro-magnet of the instrument is supported at three points, marking the corners of an equilateral triangle, and that the electro-magnet is directly active upon a point upon the plate which corresponds to the center of a circle circumscribed about said triangle. The resonant plate, therefore, is a diaphragm as distinguished from a reed, which latter is supported at one point only, and has regular pendulous vibrations; and I use the word diaphragm as descriptiveot the characteristics of my resonant plate in order to distinguish the same from reeds.

Having thus fully described my invention, what I claim, and desire to secure by Letters Patent, is-

1. In a telephone, a diaphragm tuned to respond to one rate of vibration only, substantially as described.

2. In a telephone, the combination of an electro-magnet and a diaphragm-armature in inductive proximity thereto, said diaphragmarmature being tuned to respond to one rate of vibration only, substantially as described.

3. In a telephone, a diaphragm supported at points located approximately in the nodal line or lines of the first harmonic of the said diaphragm, substantially as described.

4. In a telephone, a diaphragm free at its edge or edges resting upon points located approximately in the nodal line or lines of the first harmonic of its fundamental note, and a Weight resting upon the diaphragm, adjustable in position thereon, for tuning the diaphragm to respond to vibrations of the first harmonic only, substantially as described.

In testimony whereof I have signed my name to this specification in the presence of two subscribing witnesses.

ERNEST JULES PIERRE MEROADIER.

Witnesses:

R. J. PRESTON, ALBERT COHEN. 

